1. Field of the Invention
The present invention relates to an infra-red (IR) emitting decoy flare and in particular to a decoy flare capable of generating an IR interference cloud to divert an incoming missile equipped with an IR seeker system away from its intended target.
2. Discussion of Prior Art
One known decoy flare which is used to provide such an interference cloud is described in the patent U.S. Pat. No. 4,624,186. This flare comprises a casing containing combustible flakes and an ignition expediting material. These combustible flakes comprise a thin base material, such as paper or metal foil, on to which is pressed a phosphorous containing incendiary paste. In use, the ignition expediting material creates a fireball which passes through the combustible flakes, igniting the incendiary paste which burns to emit IR radiation. Seeker systems on incoming missiles may detect this IR radiation and be deflected from their target and toward the IR interference cloud.
One problem with this known flare is that in addition to the production of IR emission the burning phosphorous containing incendiary paste also produces visible and ultra violet (UV) emission. Some “intelligent” seeker systems can use this UV emission when deciding to ignore some IR resources and therefore not deflected from their initial target by such flares. Furthermore, some missile systems, for example ones often employed in ground based anti-aircraft batteries, require human operators to make an initial target acquisition for a particular missile before the IR seeker system of that missile guides it to its acquired target. This target acquisition is often done visually and hence, particularly at night, illumination of the target by the visible emission from the decoy flare is undesirable.
One further problem associated with the known flare is that phosphorous has a characteristic IR emission spectrum which again some “intelligent” seeker systems use when deciding which IR source to ignore.